Hydraulic valve tappet



May 30, 1939. w. D. APPEL HYDRAULIC VALVE TAPPET Filed Dec. 13, 1955 atented May 30, 1939 PATENT QFFICE Y 2,160,257 'mzmnwuo VALVE TAPPET Walter D. Appel, Pontiac, Micln, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application December 13, 1935, Serial No. 54,225

Claims.

This invention relates tohydraulio take-up mechanism in a train of motion or energy transmitting members and more specifically to a hydraulic take-up, mechanism especially adapted for use in the valve mechanism of an internal I combustion engine. This invention is an improvethese parts there is a certain amount of slack.

When the valve seats in the motor it is preferable that there be a small amount of slack in the system so that the valve willseat tightly and will not ride, due to eccentricities in the cam, which would cause a lessening of the pressure-of the valve on the seat, interfering with heat flow and increasing wear. It is also necessary to have anautomatic take-=up mechanism in normal operation as the lengths of the rigid parts change with the temperature changes and therefore change the distance between the parts and further to take up normal wear.

It is therefore an object of my invention to provicle an automatically operating take-up mechanism to take up the slack and yet adjust itself to the operating conditions.

It is a further'object of my invention to provide such a take-up mechanism which is practically made and gives satisfactory operation.

With the above and other objects in view, the embodiments of my invention reside in the disclosure as set forth. in the following specification and illustrated in the accompanying drawing, in which:

Fig. l is a sectional view through a portion of an L-head type automotive engine showing the construction and location of the device.

Fig. 2 is a sectional view through a portion of an overhead valve type of automotive engine showing the application of my invention to this type.

Fig. 3 is an enlarged elevation of the device shown in the first figure with parts broken and shown in section with the hydraulic open... l l

An automotive engine 2 has a valve 3 for the inlet or immission of gas to or from the explo- Between the valve stemand the cam sion chamber 6 said valve seating on seat 8 in the motor block l0. Through a vertical opening l2 in the block is inserted a sleeve M which is pressfitted therein and within which the valve stem ES fits for its vertical reciprocation.

To the lower projecting end of the valve stem is rigidly secured a washer l8 and surrounding the stem and the projecting sleeve is a helical compression spring 20 which bears against the washer l8 and the lower face of the block member adjacent the sleeve M which spring tends to pull the valve down firmly against the seat.

Below the valve is a camshaft 22 supported for rotation in the block and having thereon a cam {A l for operating the valve. Reciprocably sup- 15 ported in a guide 26 in the block between the valve stem and the cam is a tappet 28 which comprises an outer cup-shaped member 30 which slides upon the guide walls and whose base contacts the cam surface. The central hollow portion of the cup is of a plurality of different diameters the main portion of which is of the largest diameter and within which reciprocates in telescoping relation an inverted cup-shaped member 32. Toward the lower end of the outer member 3d the inner diameter decreases forming a shoulder tit which prevents the inner cup from telescoping into the outer beyond'this point.

The upper closed end of the member 32 has a flanged opening 36 in the center thereof, through which is adapted to project the leg 38 of an inverted T-shaped member, the lower portion of which is a flanged disk Kill. The length of the leg SS is slightly greater than the distance through the flanged opening the purpose of which will be evident as the description proceeds. The leg 38 has an axial passage 42 therethrough with which connect a plurality of radial passages M, the passage extending through the face of the disk W. Interf'orly of the two telescoping members is a helical compression spring 66 which presses I against the inner surface of the base of member 3i? and against the lower surface of the disk it to force the latter up and the outer cup down and if the travel is sumcient to tend to raise the inner telescoping cup 32.

Within the hollow portion of the outer cup above the inner telescoping member is a disk 38 the lower surface of which is flat, the upper surface having a raised central portion 553 Whose upper surface is arcuate which is adapted to contact with the lower end of the valve stem it. The disk. '38 fits loosely within the outer member and has a plurality of radial notches 52 therein.

alcove the disk lii there are cut a plurality of spaced circumferential grooves 54 and 58 into which are snapped annular collars 66 and 68 respectively. Immediately below the upper collar 68 is a flat disk 62 whose outer periphery overlaps the inner periphery of the collar to form a valve therewith. The central portion of disk 62 is flanged downwardly as at 64 and has an opening thereon through which the valve stem l6 projects. Between the two spaced collars and surrounding the lower end of the valve stem is a compression spring 66 which bears against the lower collar and against the lower surface of the disk 62 and tends to keep it against the lower surface of the upper collar. The valve stem of course slides in the central opening in the disk 62.

In the outer face of the member 38 toward the top is a circumferential groove 68 connecting with a. passage 18 extending through the wall, the groove 68 being in alignment with an oil conducting passage 12 in the guide at certain points in its movement to supply oil to theinterior of the tappet. The oil is therefore supplied through the passage 12 from any part of the engine oil pressure system and when the passage 18 is in horizontal alignment with the passage 12, oil is forced into the chamber between the two collars 56 and 68, the disk 62 acting as a closure valve in conjunction with the upper collar to prevent oil from surging from the top. This oil may then flow down through the central opening in the lower collar and through the radial notches 52 to lie over the end of the member 32.

When the tappet is idling or the parts are in the position shown in Fig. 3, the spring 46 forces the T-shaped member up until its shoulders contact the inner surface of the upper end of member 32, the leg 38 raising the disk 48 from the flanges to provide an opening 14. The oil above 32 may then flow down through opening I4, passages 44 and 42 into the interior of the telescoping members. This lower chamber is initially filled with oil and by oil flow from above is kept filled at all times in the manner of flow first set forth when the gap 14 is open.

The operation of, this device is as follows:

During inoperative periods the position of the parts is as indicated in Fig. 3 and in which the leg 38 of the T-shaped member raises the disk 48 through operation by compression spring 48 to open the gap I4. As before mentioned, the lower chamber within the telescoping member is fllled with oil and when the cam 24 raises the outer member 88, the disk 48 is forced downwardly to close gap 14 and rest upon the upper end of the flange on member 32. This seals the lower hydraulic chamber with the disk 48 resting on the flange of the telescoping member preventing any flow therefrom and the valve 4 is operated by the cam and when the latter is returned to its inoperative position, the spring 46 again raises the disk 48 therefrom to allow oil to flow to and from the lower chamber.

It will be evident that there is a short period of time between the actual application of force by the cam 24 causing a small rise in the tappet and the time at which the gap 14 is actually closed, during which time a small amount of fluid may be forced from the lower chamber due to the compression forces thereon. This action, however, is advantageous in that it would tend to carry from the lower chamber any air bubbles which may have collected, therein which will therefore rise to the top of the 'oil and be removed from that portion of the liquid which carries the transmitting force.

As before mentioned, any extra oil which may be needed to keep the lower chamber fllled at all times is supplied from the chamber above disk 48 and may drain down to fill the lower chamber at inoperative periods. It will thus be seen that the light spring 46 tends to keep the system in the correct adjustment in all inoperative periods and the enclosed hydraulic head will transmit the heavy force necessary to overcome the comparatively stiif valve spring.

In the modified form of the device as shown in Fig. 2, my hydraulic valve tappet is illustrated as appliedto a valve-in-head type motor. In this instance a motor 88 carries therein a valve 82 the stem 84 of which projects above the motor head surrounding which there is a helical compression spring 86 operating between the motor head and the washer 88 rigidly secured to the valve stem the purpose of which is to keep the valve tightly sealed. Also carried by the head is a hollow shaft 98 which carries thereon rocker arms 92 one end of which projects over and contacts with the upper end of'the valve stem to operate the same. The opposite end carries a spherical headed bolt- 94 which head engages the upper end of a vertical push rod 86 the lower end of which engages a tappet designated generally at 88 which tappet is operated by cam I88 in the camshaft I82.

The tappet in this instance is substantially the same as that set forth in the former modification with the exception that the disk 48 has been modified, its upper end having extended therefrom a semi-spherical socket I84 which extends further upward than the raised portion 58 in the former instance. Fitted within this socket is the rounded end portion I86 on the lower end of the push rod 86. Also in this instance there is no passage or circumferential groove for the immission of oil into the chamber between the two collars but the flanged disk 62' has a small opening through the center thereof adjacent end I86, the flt between the two being loose to allow oil to drain down the push rod into this chamber and so supply any extra oil which may be needed in the lower enclosed chamber between the telescoping members otherwise the operation is as in the flrst instance.

I claim:

1 In hydraulic take-up mechanism, two telescoping members one within the other and enclosing a body of fluid, the inner member having an opening thereon for fluid supply, a T-shaped valve member having its shaft projecting into the opening, resilient means acting against the valve member, a second valve member adjacent the opening and supported within the outer member against which the projecting shaft is pressed by the resilient means and a thrust transmitting member engaging the second valve member.

2. In hydraulic take-up mechanism, two telescoping members on within the other and enclosing a body of fluid, the inner member having an opening thereon for fluid supply, a T- shaped valve member having its shaft projecting into the opening, resilient means acting against the valve member, a second valve member adjacent the opening and supported within the outer member against which theprojecting, shaft is pressed by the resilient means and a fluid supply chamber adjacent the valve.

3. In hydraulic take-up mechanism, two telecoping members one within the other and form- ;ng therewith an hydraulic chamber, the inner member having an opening therein for fluid supply to the chamber, a fluid supply chamber adjacent the hydraulic chamber, aflrst valve member having a projecting portion within the opening in the inner telescoping member, resilient means acting against said valve member, a second valve member adjacent the opening and supmember having an opening therein, means 00- operating with the outer of said members to form therewith a substantially closed fluid supply chamber, a valve member having a projecting portion thereof in said opening, a second valve member adjacent the opening and supported within the fluid supply chamber, resilient means to bias the projectingportion of the first valve member against the second valve member and a thrust transmitting member engaging the sec-. ond valve member.

5. In hydraulic take-up mechanism, a hollow member closed at one end, amember having an opening therein within said hollow member and forming with the closed end thereof an hydraulic chamber, means forming a fluid supply chamber with said hollow member comprising a disc member and a resilient means for forcing said disc member to a fixed position, a T-shaped valve member having its shaft projecting into the opening, resilient means acting against the valve member, a second valve member adjacent the opening and supported within the outermember against which the projecting shaft is pressed by the resilient means and a thrust transmitting member engaging the second valve member.

WALTER D. APPEL. 

